The usual methods of depositing a metal coating on a workpiece consist in immersing said workpiece in a vessel that contains a bath of electrolyte together with electrode panels. Those methods, also referred to as in situ electrodeposition methods, present drawbacks in terms of duration and quality. Because of corner effects associated with the electric field, the deposit builds up faster at the ends of the workpiece. In order to obtain a coating that is uniform, it is therefore necessary to perform a plurality of deposition operations in succession, and interrupt them with stages of machining in order to remove the irregularities progressively. The workpiece is inserted a first time in the vessel containing the bath of electrolyte in order to receive a first deposit, then it is withdrawn from the vessel and mounted on the mandrel of a lathe so as to be machined. It is then introduced a second time in the bath of electrolyte to receive a second deposit, and the stages of deposition and of machining are thus repeated in alternation until a satisfactory coating is obtained. Methods using direct current (DC) baths generally require four to six passes, thereby giving rise to a significant loss of time and to large costs. One known solution for improving the uniformity of the deposit consists in using an alternating current (AC) bath. That technique requires only a limited number of passes and enables a deposit to be obtained that is more uniform, but it does not avoid the need for the machining stage. In addition, it gives rise to problems associated with geometry and with keeping the chemistry of the bath constant.
Another major drawback of known electrodeposition methods is the need to regenerate the bath of electrolyte regularly. In the initial bath, the concentration of ions available for electrolysis decreases as a result of the cathode reaction of deposition on the workpiece. A commonly used solution for keeping the concentration of said ions constant is referred to as “blending” the bath and consists in periodically removing a volume fraction from the bath and replacing it with an equivalent fraction of concentrated new bath. That solution remains laborious. A solution that enables the electrolytes to be regenerated continuously without external intervention is known from French patent FR 2 821 627. That document describes a method of electrodepositing nickel on a workpiece, the method involving a vessel containing a conductor material fastened to one of the end faces of the vessel and forming an anode, with a sufficient quantity of nickel beads for maintaining permanent contact with said material. The cathode-forming workpiece that is to be covered in nickel is situated under said vessel. Continuously regenerated by the nickel beads, the electrolyte comes by gravity into contact with the workpiece and is recovered below so as to be reintroduced into the vessel. That method which takes place “outside” the vessel, nevertheless does not reduce the length of time required for the mounting/removal operations prior to each stage of deposition or of machining, whenever a plurality of passes are needed.